The output power of a transmitter in a radio communication system is based upon the transmission objectives set forth for the system. These are derived from grade-of-service analyses of the results of subjective and objective tests. In digital radio systems, for instance, the problem is that in order to meet system objectives under adverse propagation conditions the power level required is considerably greater than the level needed during more normal conditions. In particular, it is only during the short periods of deep fading that high transmitter output power is required. This characteristic is peculiar to digital radio systems which can satisfactorily operate (at low error rates) very close to their threshold of operation where the error rate exceeds a certain limit. In contrast, analog FM and AM radio systems require high transmitter power at all times because of the cumulative nature of its thermal noise contribution.
It is, accordingly, the broad objective of the invention to control the transmitter output power in digital radio communication systems.